Multichannel DME ranging system

Abstract

A multichannel DME ranging circuit is described which is capable of simultaneous multistation operation. A microprocessor is coupled to control associated peripheral devices and the receiver/transmitter of a DME to produce a multiplexing for receiving frequency data input from up to three DME ground stations. The data received from each of the three DME stations is used to generate timing and interface signals to control the DME receiver/transmitter and associated video processing circuitry. The video processing circuitry is in turn used to provide signals to the ranging circuit to independently determine range, velocity, time-to-station, and the identity of each of the stations providing input to the DME. Each of the three channels is operated indpendently to produce a decoded identification of its respective ground station. The identity information can be obtained and monitored for each channel essentially simultaneously due to the fast cyclical time-multiplexed method of operation, relative to the slower identity coding scheme utilized in present distance measuring equipment.

I claim: 
     
       1. An apparatus for identifying at least three distance-measuring equipment ground stations substantially simultaneously and for decoding distance information from each of said stations, in rapid cyclical sequence, comprising: a. means for detecting first, second, and third pulsed signals from said ground stations, respectively, in sequence and in a cyclical manner, wherein said pulsed signals contain coded identifying information individual to each ground station and have a first timing characteristic, and distance information having a second timing characteristic substantially shorter than said first timing characteristic; and   b. means for operating said means for detecting, and coupled thereto, at a cyclical frequency approximately an order of magnitude faster than said first timing characteristic, and for maintaining each cyclical period at least long enough to obtain valid distance information, on the order of said second timing characteristic, at least once for each of said stations in each cyclical period.   
     
     
       2. An apparatus as in claim 1 wherein said means for detecting further comprises a programmable variable frequency receiver. 
     
     
       3. An apparatus as in claim 1 wherein said means for operating further comprises a programmable stabilized master oscillator. 
     
     
       4. An apparatus as in claim 1 wherein said means for operating further comprises means for individual automatic gain control for each of said stations in cooperation with said means for detecting and coupled thereto. 
     
     
       5. An apparatus as in claim 1 wherein said means for operating further comprises means for sampling, storing, and subsequently asserting a signal presence indication for each of said stations, one after the other, in cooperation with said means for detecting and coupled thereto. 
     
     
       6. An apparatus as in claim 1 further comprising means for decoding said identifying information, substantially simultaneously, in a coordinated manner in response to said means for operating, for each of said stations independent of the others. 
     
     
       7. An apparatus as in claim 1 further comprising means for calculating said distance information, in a coordinated periodic manner in response to said means for operating, for each of said stations, independently of the others.